1. Field
The present disclosure relates generally to an improved data processing system and in particular to a method and apparatus for routing data between different nodes in a network. Still more particularly, the present disclosure relates to a computer implemented method, apparatus, and computer usable program code for routing data between a tactical network and a satellite network.
2. Background
An ad hoc network is a network that may be dynamically formed along a group of nodes and require no existing structure or pre-configuration. An ad hoc network is dynamic and self organizing in nature. These features make this type of network particularly useful in situations in which rapid network deployments are required. A tactical network is a type of ad hoc network. A tactical network is a collection of nodes deployed in a selected geographic area that can communicate with each other.
A tactical network is typically used by different armed forces for communications in a particular location. A node in a tactical network is a data processing system that facilitates the communication of information. Nodes may be part of or located in vehicles, such as trucks or tanks. Nodes also may be carried by infantry or located on helicopters or other aircraft. These nodes are highly mobile and may frequently move with respect to each other. Nodes may join or leave a tactical network.
Tactical networks typically have limited bandwidth capacity because of the frequency spectrum in which the different nodes operate. The particular frequency spectrum used by tactical networks is based on the need to support unpredictable mobility patterns for different nodes and training requirements over which the tactical network is required to operate. As a result, bandwidth use is an important factor in tactical networks.
Further, tactical networks may be supported by another network that acts as a provider to the tactical network. One example of a provider network is a satellite network. A satellite network may provide connectivity between nodes in a tactical network as well as connectivity between nodes in different tactical networks. Additionally, a satellite network may provide services, such as communications with other networks.
A gateway is a data processing system that provides for communications between a tactical network and another network like a satellite network. Inter-network communications between a satellite network and a tactical network are provided through satellite links. These satellite links terminate in gateways in the tactical network. A gateway is a device that provides for inter-network communications. A feasible inter-network architecture for tactical networks avoids use of scarce bandwidth capacity as much as possible.
This requirement for the most part requires that traffic entering or leaving the tactical network enter or leave from an inter-network gateway that is closest to the end of the host in the tactical network. Traffic is information that is sent into or out of the tactical network. Reach back traffic is traffic entering or leaving the tactical network. Although a satellite network has more capacity or bandwidth than a tactical network, control traffic may reach levels that may cause congestion or slow downs. Control traffic is information that is sent to manage a network. The control traffic may be, for example, routing information sent from the tactical network to the satellite network for use by the satellite network to select routes to destinations within the tactical network.
Another factor that impacts the use of the bandwidth in a tactical network is the number of gateways used for inter-network communications between the tactical network and a satellite network. An increase in the number of gateways reduces the use of the tactical network capacity by reach back traffic. With more gateways, reach back traffic traverses a smaller portion of the tactical network, consuming less network bandwidth.
Although increasing the number of gateways reduces bandwidth usage in some ways, the bandwidth usage can be increased in other ways. For example, the network protocols used by tactical networks for communications within a tactical network, as well as inter-network communications with other networks, may result in performance issues and bandwidth usage.
The currently used protocols for inter-network communications were developed by the Internet community assuming a presence of abundantly available bandwidth and stable wired networks. For example, border gateway protocol (BGP) is a core routing protocol of the Internet that is used in tactical networks. This type of protocol maintains a table of IP networks or prefixes which designate network reachability among autonomous systems (AS).
The border gateway protocol may be used to exchange routing information between different gateways. The routing table maintained by each gateway contains a list of known routers where other gateways that can be reached as well as cost metric associated with a path to each router. This information is used to choose the best available route to a destination in a tactical network.
Currently, each gateway advertises all reachable addresses in the tactical network along with the cost of reaching those addresses from the gateway itself. A reachable address is an address from which a communication can be sent or received. Additionally, each gateway sends an update of an address when a gateway sees the cost of reaching the gateway from itself changing.
Every time the cost of reaching the address changes, the gateway re-advertises the address even if the gateway is not the selected point for that address into the tactical network. As a result, the frequency of updates increases as well as the number of addresses that are updated after a node changes position.
Currently, the different gateways in a tactical network pass all relevant routing information for the tactical network to the satellite network to make the necessary decisions regarding what routes to use in the tactical network. Sending this information from the gateways to the satellite network uses large amounts of bandwidth. Also, the frequency of updates adds to the consumption of bandwidth. For example, a satellite network may support numerous gateways, such as one hundred and thirty. As a result, bandwidth usage increases with all of these gateways passing information for making routing decisions to a satellite network.
Therefore, it would be advantageous to have an improved method, apparatus, and computer usable program code to reduce bandwidth usage in networks, such as tactical networks.